1,1-Dichloroethylene
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| Template:Longitem | C2H2Cl2 |
| Molar mass | 96.94 g/mol |
| Density | 1.213 g/cm3 |
| Melting point | Template:Chembox CalcTemperatures |
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| Vapor pressure | 500 mmHg (20°C)[1] |
| Template:Longitem | −49.2·10−6 cm3/mol |
| Template:Longitem | 1.3 D |
| Template:Longitem | Planar |
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1,1-Dichloroethylene, commonly called vinylidene chloride or 1,1-DCE, is an organochloride with the molecular formula Template:Chem2. It is a colorless liquid with a sharp odor. Like most chlorocarbons, it is poorly soluble in water but soluble in organic solvents. 1,1-DCE was the precursor to the original clingwrap, Saran, for food, but this application has been phased out.
Production
1,1-DCE is produced by dehydrochlorination of 1,1,2-trichloroethane, a relatively unwanted byproduct in the production of 1,1,1-trichloroethane and 1,2-dichloroethane. The conversion is a base-catalyzed reaction which uses either NaOH or Ca(OH)2 with temperature ca. 100 °C.[2]
- Cl2CHCH2Cl + NaOH → Cl2C=CH2 + NaCl + H2O
The gas phase reaction, without the base, would be more desirable but is less selective.[3]
Applications
1,1-DCE is mainly used as a comonomer in the polymerization of vinyl chloride, acrylonitrile, and acrylates. It is also used in semiconductor device fabrication for growing high purity silicon dioxide (SiO2) films.
Polyvinylidene chloride
Script error: No such module "Labelled list hatnote". As with many other alkenes, 1,1-DCE can be polymerised to form polyvinylidene chloride. A very widely used product, cling wrap, or Saran was made from this polymer. During the 1990s research suggested that, in common with many chlorinated carbon compounds, Saran posed a possible danger to health by leaching, especially on exposure to food in microwave ovens. Accordingly, SC Johnson changed their formulation of Saran Wrap in 2004 to a form of polyethylene.[4]
Safety
The health effects from exposure to vinylidene chloride are primarily on the central nervous system, including symptoms of sedation, inebriation, convulsions, spasms, and unconsciousness at high concentrations.[5]
International Agency for Research on Cancer has put vinylidene chloride in Class 2B, meaning possibly carcinogenic to humans. National Institute for Occupational Safety and Health considers vinylidene chloride a potential occupational carcinogen.[6]
See also
References
- ↑ Cite error: Script error: No such module "Namespace detect".Script error: No such module "Namespace detect".
- ↑ Course CEIC2004 Industrial Chemistry for Engineers. Chemistry Lecture Notes, UNSW
- ↑ Manfred Rossberg, Wilhelm Lendle, Gerhard Pfleiderer, Adolf Tögel, Eberhard-Ludwig Dreher, Ernst Langer, Heinz Rassaerts, Peter Kleinschmidt, Heinz Strack, Richard Cook, Uwe Beck, Karl-August Lipper, Theodore R. Torkelson, Eckhard Löser, Klaus K. Beutel, Trevor Mann "Chlorinated Hydrocarbons" in Ullmann's Encyclopedia of Industrial Chemistry 2006, Wiley-VCH, Weinheim. Script error: No such module "CS1 identifiers"..
- ↑ Script error: No such module "citation/CS1".
- ↑ epa.gov
- ↑ CDC - NIOSH Pocket Guide to Chemical Hazards